Python/IPython ImportError: no module named site

Question

I had python 2.7.3 and ipython 1.2 up and running correctly on my Linux system (ubuntu 12.04) but was trying to install a

Answer 1

you can unset PYTHONHOME to use the system default, or export PYTHONHOME=/usr to specify the prefix, to which Python will append '/lib/python2.7' (or whatever version it happens to be) to locate its libraries.

if you export PYTHONHOME=/usr/lib/python2.7, Python looks for libraries in the nonexistent folder /usr/lib/python2.7/lib/python2.7.

and if you export PYTHONHOME=, you are telling Python to look for lib in the current working directory:

jcomeau@aspire:~$ PYTHONHOME= strace -estat64 /usr/bin/python
stat64("lib/python2.7/", 0xff870ee0)    = -1 ENOENT (No such file or directory)
stat64("lib/python2.7", 0xff870ee0)     = -1 ENOENT (No such file or directory)
stat64("lib", {st_mode=S_IFDIR|0755, st_size=8192, ...}) = 0
stat64("lib/python2.7/", 0xff873efc)    = -1 ENOENT (No such file or directory)
stat64("lib/python2.7/plat-i386-linux-gnu", 0xff870ee0) = -1 ENOENT (No such file or directory)
stat64("lib/python2.7", 0xff870ee0)     = -1 ENOENT (No such file or directory)
stat64("lib", {st_mode=S_IFDIR|0755, st_size=8192, ...}) = 0
stat64("lib/python2.7/plat-i386-linux-gnu", 0xff873efc) = -1 ENOENT (No such file or directory)
stat64("lib/python2.7/lib-tk", 0xff870ee0) = -1 ENOENT (No such file or directory)
stat64("lib/python2.7", 0xff870ee0)     = -1 ENOENT (No such file or directory)
stat64("lib", {st_mode=S_IFDIR|0755, st_size=8192, ...}) = 0
stat64("lib/python2.7/lib-tk", 0xff873efc) = -1 ENOENT (No such file or directory)
stat64("lib/python2.7/lib-old", 0xff870ee0) = -1 ENOENT (No such file or directory)
stat64("lib/python2.7", 0xff870ee0)     = -1 ENOENT (No such file or directory)
stat64("lib", {st_mode=S_IFDIR|0755, st_size=8192, ...}) = 0
stat64("lib/python2.7/lib-old", 0xff873efc) = -1 ENOENT (No such file or directory)
stat64("lib/python2.7/lib-dynload", 0xff870ee0) = -1 ENOENT (No such file or directory)
stat64("lib/python2.7", 0xff870ee0)     = -1 ENOENT (No such file or directory)
stat64("lib", {st_mode=S_IFDIR|0755, st_size=8192, ...}) = 0
stat64("lib/python2.7/lib-dynload", 0xff873efc) = -1 ENOENT (No such file or directory)
ImportError: No module named site

Answer 2

PYTHONHOME

Change the location of the standard Python libraries. By default, the libraries are searched in prefix/lib/pythonversion and exec_prefix/lib/pythonversion, where prefix and exec_prefix are installation-dependent directories, both defaulting to /usr/local.

When PYTHONHOME is set to a single directory, its value replaces both prefix and exec_prefix. To specify different values for these, set PYTHONHOME to prefix:exec_prefix.

Try to clean up your PYTHONHOME:

user$ export PYTHONHOME=

As for installing matplotlib, I would recommend the following:

sudo apt-get install python-matplotlib

(details here)

Answer 3

TRY to unset your python path...

In Linux/Mac, you can use these commands:

unset PYTHONPATH
unset PYTHONHOME